Purification of vitamin a esters



Patented July 15, 1941 PURIFICATION OF VITAMIN A ESTERS Kenneth C. D. Hickman, Rochester, N. Y., as-

signor to Distillation Products, Inc., Rochester, N. Y., a corporation of Delaware No Drawing.

9 Claims.

This invention relates to improved procedure for the preparation of purified Vitamin A ester concentrates. More particularly, it pertains to improved methods for removing Vitamin A ester concentrates from substances which impart undesirable odor and taste or which haveno vitamin potency.

Vitamin A is now known to occur in natural fish oils in the ester form. These esters can be concentrated by molecular distillation. 'When putrid oils are distilled, and in some cases when ordinary oils are distilled, certain fractions are obtained which are odoriferousand/or contain undesirable constituents such as sterols, free fatty acids, coloring matter and other substances which are undesirable but which are difiicult to separate. When Vitamin A esters are prepared by synthetic means, such as esterification of Vitamin A alcohol, the ester product contains impurities and unreacted VitaminA alcohol. -It is desirable to separate the impurities and particularly the unreacted alcohol since it rapidly loses its vitamin potency. Until the advent of my in- Application February 11, 1939, Serial No. 255,928,

.a more or less degree in the alcohol solvent. This I is not particularly disadvantageous sincethe alcohol, after separation from the main body'of the concentrate, can be treated to recover the Vitamin A ester. This can be easily accomplished by distilling off the alcohol in a vacuum.

The alcohol dissolves-much of the impurities from the vitamin concentrateand these impurities in many caseshave decided value. For m stance cholesterol can be recovered from the alcohol solvent and sold as a commercial product.

vention no method was known for separating I Vitamin A ester from Vitamin A alcohol.

This invention has for its object to overcome the above difiiculties. Another object is to provide a process for separating impurities and other undesired constituents from Vitamin A ester concentrates prepared by distillation, esterification or otherwise. Another object is to'provide a simple procedure for separating Vitamin A alcohol from Vitamin A esters. Other objects will appear from the following description and claims.

These and other objects are accomplished in accordance with my invention which includes extracting the impurities from the Vitamin A ester with an alcohol.

I prefer to employ ethyl alcohol for this'purpose, but lower aliphatic alcohols are in general useful. Methyl and ethyl alcohol are superior for this purpose.

The Vitamin A ester concentrate and the alcohol may be contacted in any desired manner. It is apparent that intimate contact between the two materials must take place. The simplest procedure would be to mix the two materials in a simple shaking equipment. Usual extraction apparatus may be used but I prefer to employ small amounts of other solvents or water can be used quite satisfactorily. .In some cases, such diluted solvents are preferred, such as for instance in connection with the separation of Vitamin A ester from Vitamin A alcohol. Alcohol of approximately 83-85% strength, the balance of which is water, is preferred for this extraction since the alcohol form of the vitamin is.sub-

stantially soluble in this solvent while the Vitamin A ester is substantially insoluble therein.

ExainpZeI Second fraction distilling betweenl-210 C.

from pollack-liver oil is passed counter-current. through 95% ethyl alcohol, the distillate and the alcohol being in .the proportion of two volumes to three, respectively. Much of the'cholesterol, the free fatty acid, and the fish odor pass into the alcohol. Part of the Vitamin A also dissolves in the alcohol, but this can be recovered later.

Example II Vitamin A alcohol produced by saponification of a crude fish oil or of a molecular concentrate is allowed to react with acetyl chloride in pyridine.

A alcohol. The mixture is freed from pyridine and volatiles by distillation in a vacuum and'is then passed counter-current through 85'per cent ethyl alcohol. The unesterified Vitamin A dissolves in the solvent, and the Vitamin A acetate remains in the raflinate.

Procedure for preparing Vitamin A in ester form either by high vacuum distillation or by f The product of the reaction is essentially Vitamin A acetate with some unchanged Vitamin Y synthetic means is well known in the art. The distillation procedure involves heating a fish oil under a high vacuum and condensing vapors upon a condensing surface separated from the heated oil by unobstructed space. For further details reference is made to Hickman Patent 1,925,559 and Hickman applications 39,148, filed September 4, 1935; 56,587 filed December 28, 1935; 112,847, filed November 27, 1936; and 174,491, filed November 13, 1937.

What I claim is:

1. The process of purifying a concentrate of a carboxylic acid ester of vitamin A which contains impurities of the kind selected from the group consisting of impurities normally present in a reaction mixture from an esteriflcation of vitamin A alcohol and impurities normally present in a vitamin A concentrate derived from a fish oil which process comprises extracting the impurities from the concentrate by contacting it with an alcohol selected from the group consisting ofmethyl and ethyl alcohol and separating the alcohol containing the extracted impurities from the concentrate being purified, the impurities present being substantially soluble in methyl or ethyl alcohol.

2. The process of purifying a .vitaminous substance which comprisestreating a concentrate of a carboxylic-acid esteroi' vitamin A, derived from a fish oil and containing impurities asso-' extracting the impurities from the concentrate by contacting it with ethyl alcohol and separating the alcohol containing the extracted impurities from the concentrate being treated the impurities present in the concentrate being to a substantial extent soluble in ethyl alcohol.

4. The process of purifying a concentrate of a carboxylicacid ester of vitamin A derived from a fish oil and containing impurities normally associated therewith which process comprises extracting the impurities from the concentrate by contacting it with approximately 85% ethyl alcohol and separating the alcohol containing the-extracted impurities from the concentrate being treated the impurities present in the concentrate being soluble to a substantial extent in ethyl alcohol.

5. The process of purifying a concentrate of vitamin A in ester form which has been produced by high vacuum distillation of a flsh oil containing vitamin'A ester, which process comprises extracting the impurities from the concentrate by contacting it with ethyl alcohol and separating the alcohol containing the extracted impurities from the concentrate being treated.

6. The process of purifying a concentrate of vitaminlA in ester form, which concentrate has been produced by high vacuum distillation of a fish oil which contains vitamin A esters, which process comprises extracting the impurities from the concentrate by contacting it with about 96% ethyl alcohol and separating the alcohol containing the extracted impurities from the concen- I trate being treated.

7. The process of claim 6 wherein countercurrent contact between theconcentrate and the alcohol takes place during the extraction.

8. The process of purifyin a concentrate of a carboxylic acid ester of vitamin A which has been produced by esterifying vitamin A alcohol derived from a fish oil and containing impurities associated with said fish oil and those formed during the esterification reaction which process comprises extracting the unreacted vitamin A alcohol and other impurities from the concentrate by contacting it with approximately 85% ethyl alcohol and separating'the alcohol containing the extracted impurities including the unreacted vitamin A alcohol the impurities present in the concentrate being substantially soluble in 85% ethyl alcohol. r

9. The process of purifying a synthetic concentrate of a carboxylic acid ester of vitamin A which has been produced by esterification of vitamin A and which contains unreacted vitamin A alcohol KENNETH C. D. HICKMAN. 

